If you’re a savvy shopper, you’ll know the thrill of getting the bus to the nice side of town to visit the posh Oxfam to see what’s on the rails. There, you wallow in yesteryear’s fabulosity, cast off by someone whose spending habits you’re morally outraged by but whose taste you can’t fault.

Except with this secondhand spree, you won’t be checking for mothball smells or armpit stains, or wondering if anyone died in it – you’ll be nodding in sweet, misty-eyed reverie as you recall the precise occasion when each piece was worn.

Like it or not, these clothes are the backdrop to the past 15 years of your existence. You might not know them individually but you’ll be aware of the different incarnations of the woman who wore them, from girl power to bling to bottle blonde to now: respected fashion designer, witty and wry mother of four.

The sale of the 600-plus pieces may or may not have something to do with the fact, revealed in Vogue recently, that the Beckhams are in the throes of having their new home remodelled by one of London’s most exclusive interior designers. Who hasn’t moved house and chucked a load of old stuff just because they can’t face ramming it back into the Ikea chest of drawers? Celebrities are just like us, really.

That’s why it makes sense to invest a couple of thou in some of Victoria’s old togs – you never know when you’ll need a red carpet gown slit to the hip and covered in giant frilly flowers. “It’ll come in handy one day,” you think, clearing space for it in between your dressing gown and a Marks & Spencer suit. “It’ll do for weddings.”

This isn’t the first time she has sold pieces from her personal collection. Last time her clothes overflowed the Petit Trianon she houses them in, she eBayed some for the good of typhoon victims in the Philippines. Kim Kardashian got in on the act, too – until it emerged she was sending just 10% of the profits to the needy, thereby proving that British celebs are better than American ones.

So who buys Victoria’s castoffs? There aren’t enough Spice Girls fans with the cash – that much was proved by the six-month run of West End musical Viva Forever. Oligarchs’ wives, perhaps, or the same rich fruits who snapped up Margaret Thatcher’s suits from Christie’s.

There might be one or two low-impact day dresses that go for around the £200 mark – these will be eagerly bought by aspiring husbands of would-be glamourpusses. convinced that fame will rub off on to them like makeup. These will be presented on birthdays, then worn to regional gastropubs accessorised with a “you heard me” look.

More probably, though, it will be collectors and archivists who will bid on these pieces: curators with holes in their collections and museums looking to add a bit of star quality to their vitrines. Although Victoria is a populist icon, her wardrobe is relatively rarefied; sneer at it now but scholars may pore over that Cavalli one day.

So while you might not be getting your purse out, don’t dismiss this sale as money for old robes. These dresses have become a sort of Heat magazine history lesson in status, reinvention and celebrity culture. And they’ll be a great talking point at the wedding breakfast.